Project 3 will focus on two primary goals. The first concerns the neuroanatomical changes that occur with age and their relationship to neuropsychologic test scores and quantified electrophysiologic measures. Toward this end, data from 200 optimally healthy subjects (approximately 100 males an 100 females) will be examined. Most of these data will have been gathered in the previous funding period, however, some data will be gathered in the present application in order to permit the collection of gradient echo images on all of the subjects. A variety of statistical techniques will be employed to evaluate age-related change. The second primary goal of Project 3 concerns dementia of the Alzheimer type (AD). One hundred and twenty five questionable cases of AD (CDR=0.5) and forty normal controls (CDR=0) will be followed for a minimum of 3 years. it is anticipated that approximately 2/3 of the questionable cases (n=80) will be categorized as AD by the end of the follow-up period. This will permit an examination of the neuroanatomic differences between questionable cases who are diagnosed as AD on follow-up and questionable cases who are not. It will also permit the evaluation of the relationship between MRI measures, neuropsychologic test scores, and neuroimaging measures of brain function (i.e., quantified EEGs and EPs and Single Photon Emission Tomography).